1. Field of the Invention
The present invention relates to communications and computer systems, and more particularly to system architectures which provide a broad spectrum of services simultaneously to a large number of users.
2. Description of the Prior Art
Present day communications and computer systems employ codes for the transmission and storage of data, such as ASCII. Transmission techniques frequently include various forms of multiplexing of the information. The storage of information is generally in the form of the standard codes wherein the number of bits in a character generally determine the size of the character set. Many techniques are known for increasing the amount of data which can be transmitted with a given number of bits, such as the use of shift, i.e. upper and lower case. Generally, a site receives and/or transmits data to one other site at a given time, since simultaneous communication by a site with a plurality of other sites is generally not economical as it involves allocation of several channels, increase of bandwidth or additional hardware at the switching centers, and, the receiving and sending sites. Communications normally occur over frequency division multiplexed (FDM) channels even when the transmitted data is digital. Such FDM channels have guard bands to protect against interchannel interaction. Such guard band wastes spectrum but are a necessity and require the use of many costly filters. The data sent over an FDM channel might be digital data from either a modem or a digital gate. Digital channels, when time shared by the use of time division multiplex (TDM) signals, tend to have unfilled areas further contributing to the waste of spectrum. The use of the full wire bandwidth and use of unassigned TDM slots are desirable to obtain increased efficiency.
The computer has grown from a simple bulk processor using mechanical relays to a time sharing device, to a multiprocessor, mini-computer, and micro-computer on a single chip. But the basic form of computer architecture generally still employs a central processing unit (CPU). The CPU has become a more complex machine in order to handle the additional requirements imposed by competition. Nevertheless, the present day CPU operates on the same basic principles as used in the original machines. The CPU is still a major throughout path since it performs and controls most operations. Multiprocessing represents one effort to increase the throughput of computers by permitting several processing operations to occur simultaneously.
In the conventional computer, interface terminal units and other software or hardware are required to permit access to the computer by the external user. Techniques such as polling are used to permit access by the user at an alloted time. Polling requires spectrum and adds to the complexity of both the sending and receivng sites. Where the computer must dial the user through a switching center, further complexity results. Also, intelligent terminals have increasingly been used with computers and serve to reduce the load on the main computer and, consequently, reduce the cost to the consumer for computer time. The intelligent terminal performs many operations formerly alloted to the main machine, frequently under the direction of mini or micro-computers. Still, the intelligent terminal adds its own complexity to that of the main computer system.
It is an object of the present invention to provide a communications and/or computer system which can service a very large number of on-line users simultaneously and in an effective, efficient and economic manner. It is another object to increase the amount of data which can be transferred or stored with a given number of bits. It is another object to provide a communications system which permits immediate service to the users without going through switching centers. It is another object to provide a communications system which permits a station to be accessed by a plurality of users at a given time. It is another object to provide a computer which simultaneously services a large number of users. It is another object to provide a computer with high throughput and which can execute a multiplicity of different operations or processes simultaneously. It is another object to provide a communications and/or computer system which can increase in size and capability by the addition of processors and other sites.